Non-invasive Densitometric and Histomorphometric Study of the Regenerated Bone in the Distraction Gap in Rabbits.

牵张完成后长时间的外固定是牵张成骨的一个重要缺点，这是在不固定的情况下获得足够的抗力所必需的。本研究的目的是了解再生骨的力学性能，并试图找到安全取出固定器的合适时机。将外固定装置应用于兔右侧胫骨，并在胫腓骨交界处下方进行横形截骨术。术后胫骨平均延长7.2 mm，平均每天0.72 mm，连续10天。外周定量CT骨密度和应力应变指数在牵张结束后第40天有明显增加，但在牵张结束后恢复到对照水平。因此，在本研究的巩固期间，宿主皮质骨之间的新形成的骨似乎足以抵抗第40天的机械应力。本研究结果提示，在固位期BMD和SSI显着升高的时期，拆除固定装置是可能的。

The long period of external fixation after the completion of distraction, which is necessary to obtain enough strength for resisting without fixation is a significant disadvantage of distraction osteogenesis. The purpose of this study is to understand the mechanical property of the regenerated bone and try to find an appropriate timing for safely removing the fixation device. A external fixation device was applied to the right tibia in rabbits and transverse osteotomy was performed just below the tibio-fibula junction. The tibiae were lengthened 7.2 mm at 0.72 mm a day for 10 days after surgery. A.bone mineral density (BMD) and stress strain index (SSI) analyzed by peripheral quantitative computed tomography showed a significant increase on day 40, but returned to the control level at day 64 after the completion of distraction. Therefore, the newly formed bone between the host cortical bone seemed to be enough to resist the mechanical stress on day 40 during the consolidation period in this study. The present results suggested the possibility of removing the fixation device during the period when the BMD and SSI showed a significantly high level during the consolidation period.